The benefits of 3D printing in refrigeration and air conditioning
The various applications of 3D printing in the field of refrigeration and air conditioning highlight possible tremendous advantages in terms of energy efficiency and cost minimisation.
Additive manufacturing, also known as 3D printing, is a transformative approach to industrial production that allows to create lighter, stronger parts and systems. It is another technological breakthrough made possible by the shift from analogue to digital processes.1
Additive manufacturing uses computer-aided design (CAD) software or 3D object scanners to direct material to be deposited, layer by layer, in precise geometric shapes.1
The term "additive manufacturing" refers to technologies that allow three-dimensional objects to be shaped layer upon layer. Each successive layer binds to the previous layer of molten or partially molten material. Different substances can be used for the lamination of materials, including metal powder, thermoplastics, ceramics, composites, glass, and even edible products such as chocolate.1
Objects are digitally defined by computer-aided design (CAD) software that is used to create .stl (stereolithography) files that essentially "slice" the object into ultra-thin layers. This information guides the path of a nozzle or print head that precisely deposits the material on the previous layer. Or, a laser or electron beam selectively or partially melts in a bed of powdered material. As the materials cool or harden, they fuse together to form a three-dimensional object.1
A young German company called re-generate is working with researchers and industrial partners to introduce additive manufacturing to the HVAC&R industry. The initial goal is to develop market interest in more compact and lighter heat exchangers printed in 3D.2
The company believes that this manufacturing process can enable faster innovation cycles with immediate production of prototypes, save money by reducing the need for complex traditional tools, and reduce the carbon footprint by reusing materials and using decentralised production. Nina Masson, founder and CEO of re-generate said: "We believe in efficient technology, better design and a smaller environmental footprint in future HVAC and refrigeration solutions. She added : “3D printing helps our partners shape a smarter heating and cooling business, while delivering in all three areas.”2
One of the advantages of 3D printing, compared to traditional moulding and casting methods, is that a wider variety of materials can be used, including metals, ceramics, silica and plastics, increasing the potential application areas. 2
In the case of small 3D printed heat exchangers, their potential applications are currently considered to be any installation where space is limited and spatial flexibility is required. Applications currently being proposed include residential and mobile air conditioning, heat pumps and any application where microchannel heat exchangers are used today. 2
In a previous project, scientists at the Fraunhofer Institute reportedly proved that 3D printing technology can reduce the size of heat exchangers while increasing their efficiency. They say they have improved the compactness of the 3D-printed heat exchangers by more than 50% compared to the reference heat exchangers, and thus increased the efficiency per volume from 46% to 126%. In their project, water was modelled as a cooling medium.2
In addition, the University of Maryland in the United States, with its partners 3D Systems and the US Department of Energy, has designed a prototype heat exchanger that would be 20% lighter and 20% more efficient than the heat exchangers currently in use.3
This prototype is intended for use in air-conditioning units. The microscopic layers of the 3D printing allow the heat exchanger to include 200 micrometre thick walls that are still capable of withstanding extremely high pressures. This makes it both lighter and more efficient and can expand the range of materials that could be used to make heat exchangers.3
Most heat exchangers are made of metal because metal is strong and highly conductive, which facilitates heat transfer. The 3D-printed heat exchanger is constructed using a continuous printing process that produces a seamless solid object that will not leak. This extends the service life of the heat exchanger as well as all other parts of the air conditioner. It also reduces the risk of soiling. Fouling occurs when an external material creates deposits in the heat exchanger's passageways and interferes with the flow of air or liquids.3
The technology seems very promising, but the question remains as to whether, despite its current high cost, it will really be able to be part of the development and manufacturing process of HVAC&R equipment.